A discussion of waste-to-energy (WTE) among waste management professionals can generate a lot of heat. Some professionals feel WTE should be the cornerstone of large, complex waste management systems. Others feel that WTE is environmentally destructive and toxic to humans, while advocates of recycling may fear that it preempts any hope of recycling a large portion of the waste stream.
There is a place for WTE within the field of waste management but its use is specific and not universal. For communities considering WTE, here are some guiding principles to keep in mind:
The U.S. Environmental Protection Agency's (EPA) solid waste hierarchy:
Recycling or composting;
Combusted with energy recovery; and
Landfill or incineration without energy recovery.
Solid waste systems and services should be reliable.
Systems should be environmentally beneficial or benign.
The system's direct and indirect cost should be calculated over its life.
In communities that use WTE, recycling needs to happen first, and WTE can then process what cannot be reasonably and reliably recycled at a high and sustainable rate, meaning a recycling rate of at least 50 percent. WTE facilities should be sized to process the waste left over after recycling program goals are met and transform it into electricity. If steam sales and/or district energy customers are available, a co-generation plant should be included. Although our society is becoming smarter in generating less waste when making and delivering goods to consumers, historical waste generation rates show that our waste quantities continue to grow as our population increases.
In 2004, a survey of U.S. WTE facilities by the Integrated Waste Services Association, now the Washington-based Energy Recovery Council (www.energyrecoverycouncil.org) took a look at the effect WTE facilities have had on local recycling efforts. Data from EPA for the study year showed the overall municipal recycling rate in the United States to be 31 percent. By comparison, the 94 WTE communities contacted for this investigation had an average recycling rate of 34 percent. Ten years ago, WTE communities had an average recycling rate of 21 percent versus the national rate of 17 percent. Simply stated, there does not have to be a conflict; the two approaches can coexist and support an overall goal of minimizing what ends up in a landfill.
Of the 89 WTE facilities in the United States, 10 produce refuse-derived fuel. In these facilities, waste that has already been sorted for recyclables is processed again to recover additional recyclables. Using RDF in more electrical plants or industrial boilers is a way to increase the use of alternative fuels and increase recycling.
WTE and the Environment
According to EPA, 254 million tons of municipal solid waste were generated in 2007. This waste was managed in three ways: 33.4 percent was recycled, 12.6 percent went to WTE facilities, and the remaining 54 percent was landfilled. WTE facilities exported the equivalent of 2,300 megawatts of electricity to the power grid, while a few — such as those in Baltimore and Indianapolis — also distributed steam to downtown district energy loops. Their emissions meet or are below air pollution standards under the Clean Air Act (CAA), and they dispose of their ash products in regulated Subtitle D landfills safely without undue impact on the environment.
The environmental performance of these facilities speaks for itself. Today, WTE facilities have virtually no cumulative dioxin emissions, and they have achieved a 60-fold decrease in mercury emissions between 1987 and 2000, according to EPA. If you wonder how they are performing, take the time and review the environmental and safety performance of facilities such as those located in Alexandria, Va.; Baltimore; Modesto, Calif.; Miami; or Montgomery County, Md.
The regions of Durham and York in Ontario, Canada, (see www.durhamorkwaste.ca) found significant environmental benefits to WTE when comparing systems with a WTE facility located 75 miles away to one with a remote landfill located 300 miles away (assuming a 60 percent recycling level in both systems). An independent analysis found these alternatives to be economically comparable and noted that potential revenues from the sale of carbon credits and having a system less susceptible to inflationary transportation costs would make the WTE system even more economically attractive over the long term.
Fairfax, Va.-based Gershman, Brickner & Bratton (GBB) recently used the EPA's Waste Reduction Model (WARM) to compare the environmental benefits of systems with 50 percent recycling with different disposal components. The WARM modeling showed that a system with WTE compared to one either with mixed waste composting or landfilling as the primary disposal option was environmentally superior because of an additional 10 percent greenhouse gas reduction.
So, the question becomes, “If WTE facilities are environmentally beneficial and compatible with recycling, then why aren't more communities making them the centerpiece of their strategic vision?” The answer: money and siting.
WTE facilities cost a lot to build, and landfill disposal in the United States is relatively inexpensive even when the landfills are remotely located. GBB's recent analysis for systems with WTE bears this out. Disposal cost needs to approach $100 per ton before WTE becomes economically viable: the larger the WTE facility, the lower the WTE costs; the higher the price paid for electricity, the lower the cost; if cogeneration can be included, the lower the cost; if ash disposal can be cost-based versus market-price-based, this lowers the costs even further. Access to credit and financial markets for the capital cost is a major concern given the current economic climate.
Siting a WTE is a whole other issue, one best addressed in its own article.
What's Going On
Many local governments are evaluating various waste conversion technologies such as anaerobic digestion, acid catalysis and distillation, gasification/pyrolysis, and plasma-arc. There are a host of risks associated with these technologies, such as moving from pilot plant size to significantly larger units, environmental impacts, cost uncertainties, market uncertainties, siting and permitting needs and community acceptance, to name just a few.
Don't forget that some of these technologies have been tried before by major corporations in the 1970s, and their large-scale efforts in places like Baltimore, San Diego, and Charleston, W.Va., ended up failing. There are now well over 100 companies advancing emerging conversion technologies, according to GBB's database. However, the projected economics should be cause for concern. A review of the 22 conversion technology firms evaluated by New York City and Los Angeles shows their costs ranging from $136 to $900 per ton for technologies that included gasification, plasma arc, anaerobic digestion, pyrolysis and mass-burn WTE. Proposed WTE costs generally held to the low end of the range reported. Overall net economics, i.e., the service fee required by the contractor, are uncertain as these emerging technologies have yet to operate at significant levels of throughput.
Meanwhile, after years of dormancy, WTE is starting to move again with facility expansions in Baltimore; Hillsborough County, Fla.; Lee County, Fla.; Honolulu; Olmsted County, Minn.; and Pope/Douglas counties, Minn. Furthermore, new projects are being developed in Frederick and Carroll counties, Md.; Harford County, Md.; Palm Beach County, Fla.; and the U.S. Virgin Islands.
Hopefully, WTE will be included in the national renewable energy standard so that this homegrown renewable energy can be more fully utilized. This will change nearly 30 years of federal law, as well as acknowledge laws in 25 states that recognize WTE as renewable. Inclusion of WTE will rightfully place the communities that own or rely upon these facilities on a level playing field with other renewable resources. In addition, inclusion will expedite the reduction of greenhouse gases and support efforts to increase use of alternative and renewable homegrown fuel sources. Upon such inclusion, 50 percent of any incremental financial benefit received due to being designated as a renewable facility should be directed to participating local governments for the purposes of growing and maintaining reduce/reuse/recycling programs aimed at reaching diversion levels of at least 50 percent.
A partnership between recycling and WTE can increase the amount of renewable energy produced in this country and accelerate growth in sustainable recycling programs at the same time.
Want to Know More?
Harvey Gershman will speak in further detail on these issues at the “Waste Conversion Technologies: Fact or Fiction” session at WasteExpo on Tuesday, June 9. The session, which is part of the Green Technology Track, will run from 10:15 a.m to 11:45 a.m.